Cell-free DNA (cfDNA) is present in various body fluids and originates mostly from blood cells. In specific conditions, circulating cfDNA might be derived from tumours, donor organs after transplantation or from the foetus during pregnancy. The analysis of cfDNA is mainly used for genetic analyses of the source tissue —tumour, foetus or for the early detection of graft rejection. It might serve also as a nonspecific biomarker of tissue damage in critical care medicine. In kidney diseases, cfDNA increases during haemodialysis and indicates cell damage. In patients with renal cell carcinoma, cfDNA in plasma and its integrity is studied for monitoring of tumour growth, the effects of chemotherapy and for prognosis. Urinary cfDNA is highly fragmented, but the technical hurdles can now be overcome and urinary cfDNA is being evaluated as a potential biomarker of renal injury and urinary tract tumours. Beyond its diagnostic application, cfDNA might also be involved in the pathogenesis of diseases affecting the kidneys as shown for systemic lupus, sepsis and some pregnancy-related pathologies. Recent data suggest that increased cfDNA is associated with acute kidney injury. In this review, we discuss the biological characteristics, sources of cfDNA, its potential use as a biomarker as well as its role in the pathogenesis of renal and urinary diseases.

中文翻译：

---

无细胞 DNA：在病理生理学中的作用和作为肾脏疾病的生物标志物

游离 DNA (cfDNA) 存在于各种体液中，主要来源于血细胞。在特定条件下，循环 cfDNA 可能来自肿瘤、移植后的供体器官或怀孕期间的胎儿。cfDNA 分析主要用于源组织（肿瘤、胎儿）的遗传分析或用于移植排斥的早期检测。它还可以作为重症监护医学中组织损伤的非特异性生物标志物。在肾脏疾病中，血液透析期间 cfDNA 增加并表明细胞受损。在肾细胞癌患者中，研究血浆中的 cfDNA 及其完整性以监测肿瘤生长、化疗效果和预后。尿液 cfDNA 高度碎片化，但现在可以克服技术障碍，并且正在评估尿液 cfDNA 作为肾损伤和尿路肿瘤的潜在生物标志物。除了诊断应用之外，cfDNA 还可能参与影响肾脏的疾病的发病机制，如系统性狼疮、败血症和一些与妊娠相关的疾病所示。最近的数据表明，增加的 cfDNA 与急性肾损伤有关。在这篇综述中，我们讨论了 cfDNA 的生物学特征、来源、其作为生物标志物的潜在用途以及它在肾脏和泌尿系统疾病发病机制中的作用。最近的数据表明，增加的 cfDNA 与急性肾损伤有关。在这篇综述中，我们讨论了 cfDNA 的生物学特征、来源、其作为生物标志物的潜在用途以及它在肾脏和泌尿系统疾病发病机制中的作用。最近的数据表明，增加的 cfDNA 与急性肾损伤有关。在这篇综述中，我们讨论了 cfDNA 的生物学特征、来源、其作为生物标志物的潜在用途以及它在肾脏和泌尿系统疾病发病机制中的作用。